MG-Cars.info

Welcome to our Site for MG, Triumph and Austin-Healey Car Information.

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG TD TF 1500 - Rollbar project

Here are the first pictures of my latest project - a completely removable rollbar for my 51 TD. I'll start posting more as I wrap it up. Currently, all that's left to be done is to make the plywood bench, paint the rollbar, and put everything back in.
This rollbar mounts to six large 1/4 inch plates which are flush with the base of the rear plywood floor. Underneath, a mounting platform was built consisting of two rear plates and two front mounting platforms. The rollbar bolts into place. Everything is oversize: 1/4 steel plate, 0.126 DOM 1.5 inch tubing, and 2" square tube mounting brackets.
I'll post a bunch of photos first and later on I'll describe the process and why I chose this particular design.

Geoffrey M Baker

Here is the rollbar sitting in the back of the MG

Geoffrey M Baker

Here is the front right mounting bracket. The mounting bar with the four front plates slides into this set of brackets and is bolted into place. When complete, I will then weld the bar permanently into place. This system allowed me to build a removable set of mounts which I could then do all the welding on easily, out of the car, and upside down. Then I flipped it up and slide it into place and weld it permanently.

Geoffrey M Baker

Here is the central bar which will hold the four front mounting plates, with bolt holes visible.

Geoffrey M Baker

Here is a shot of the right front floor mount plate, which has been tack welded into place before final welding. Due to a 1/4 tilt in the car tub, I've added an extra 1/4 plate as a shim.

Geoffrey M Baker

The mounting plates have 3/8 nuts welded beneath.

Geoffrey M Baker

I'll post more pictures as I button up the project.

The requirements were that it had to fit under the convertible top and allow the top to be raised and lowered with the rollbar in place; and that the rollbar should be completely removable allowing the car to revert to (nearly) it's original specs.

I want to thank the many people who posted their takes on rollbars, and to Hiram Kelley in particular who supplied me with pictures and pdfs of his racing rollbar setup, including dimensions and costs.

Now I should say right away that while I was aiming for safety, I make no attempt to meet or exceed any road safety standards with this setup. Racing regulations require rollbars be higher to protect helmeted drivers. Also, because my rollbars had to fit under the convertible top, racing rollbars would offer more protection in the side and shoulder areas (as they would project outwards in these areas). My rollbar sits about one inch over my head.

My priorities though, were that the materials should all exceed current racing requirements in terms of strength of materials. (I used DOM tubing 1.5 inches in diameter and 0.12 thickness, which is thicker than required.)

I also wanted an simple mount-and-remove system, using plates with large bolts throughout.

And it had to fit in the back without requiring major changes to the tub, upholstery or seats.

Here's what I did.

I removed the rear wooden plywood frame behind the seat and took the seat out. The chassis was exposed.

I welded four brackets onto the two rear crossmembers. The rear brackets are just simple plates that weld flat to the chassis.
The front brackets are much more complex. First, in figuring out what I needed to do, I realized that I wanted to mount a transverse bar for additional strength, and that it should run between the crossmembers, and the transverse bar would hold the front brackets for the roll bar. I purchased two pieces of 2x1/4 square tube, the kind that are used in heavy duty hitches. I also purchased a long piece of 1.5 x .125 square tube, which fits neatly inside the larger square tube.

By cutting an angle on the bottom of the 2 inch square tubes, I could mount them vertically and weld them to the chassis. However, I felt I needed more, so I cut a long triangular fillet of 1/4 steel plate and welded that to the square tubes, and welded both whole assemblies to the two chassis members. Now I had a strong rigid platform to mount my transverse bar.
I cut two short pieces of the 1.5 x .125 bar and filed the 2 inch tubes so they were a perfect sliding fit. Then I drilled bolt holes (3/8 bolts) so I now had a boltable mounting platform.
Next I welded those two short piecees to the long transverse piece. Because these needed to be strong, I ground all the edges to 45 degree angles so I could run fillet welds all around the joint, and then I welded INSIDE the pieces so the interior of the tube was welded, for maximum strength.
Now I had a transverse bar with two mounts that slots right into the chassis and bolts in place.
Why did I use a bolting system for this part of the project?
I did this because I wanted to be able to weld the flat plates thoroughly on the underside of the transverse bar, and I'm not good enough to do upside down welds, nor do I have a means of raising the car high enough to do this from underneath! By using a bolting system, I could take the crossmember OUT of the car and weld my four mounting plates to the bar upside down - being able to easily and cleanly weld every inch of it... then turn it rightside up and slot it in and bolt it in place. When it's all done, I plan to fillet weld the transverse bar to the chassis mounts anyway, just for maximum strength. But it greatly simplified my welding process.
Now I have the chassis mounts, the transverse bar slotting into the mounts, and four sets of 4 x 4 square 1/4 plates all mounted on the transverse bar. Two 1.5 x .125 hoops will be welded to these plates, completing the front section of the rollbar. Then two diagonal rear braces will mount from the front hoops to the rear plates, and it's done.
All of it can be unbolted at any time.
Strength? Well, I believe it is as strong as any commercial rollbar out there, with one caveat; it's not sized properly (being too short for racing, which requires clearance for your helmet) and the diagonal braces may not be "code" either, in terms of the angles used.
But it's massive, strong, and looks good... and can be easily removed.
Because there are 6 new square holes cut through the flooring in the rear, I decided to add a draft excluder, or else air and exhaust would flow up easily. So I just took a sheet of aluminumn and set it in first, directly above the base mounting plates, and cut holes through the draft excluder for all the bolts. Then the plywood is fitted in and the roll bar bolted in last. So there is zero air movement through the floor area.


Cost: $61 for steel (8 4x4 1/4 plates, 3ft of 3 inch 1/4 stock, two 6 inch 2x2 1/4 tubes, one eight foot section of 1.5 x .125 square tube (remnant).
$26 hardware (28 3/8 bolts with washers and nuts) from ACE hardwear - you could buy them cheaper I'm sure.
$45 for 15 ft 1.5 x .125 DOM (drawn over mandrel) tubing
$30 for bending services for the DOM tubing.
$18.98 for 36x36 aluminum plate (draft excluder) Home Depot
$15.25 for 15/32 sanded plywood flooring Home Depot

Fun project, and very good peace of mind for the money!

Next: add 3-point seatbelts! And headrests, right away!

Absolutely essential tools:
A metal cutoff circular saw (cheap on Harbor freight). I used a six inch, an eight inch would be much preferable but a bit more expensive.
A wire feed welder. These welds are too long to do with a stick unless you are really expert; but with a wire feed welder a novice like myself can do them with ease. I only have a stick welder, I borrowed a nice Lincoln wire feed from a generous friend.
A die grinder and 4.5 inch angle grinder... very very helpful for cutting and cleaning up surfaces and welds.

Thoughts throughout the process: I probably oversized most everything; you could use .125 thickness steel throughout and 0.95 for the DOM tubing, as well as smaller front plates (3x3) at 3/16 thickness. All of this would still be acceptable for racing! You can also save labor by buying predrilled mounting plates - drilling my plates individually took quite a while and was not a significant savings (the plates were 98 cents each, predrilled smaller ones would not be much more expensive).

Things one could add:
You could add "wings" to the sides, offering more protection in the shoulder area, by welding on a little more DOM tubing.
If you are willing to sacrifice rear vision, you could add more diagonal tubing by welding an X between the rear rollbars.
Geoffrey M Baker

Interesting design idea. I have yet to decide how to proceed with mine quite yet. I'm 6'2' and a legal roll bar is going to be very tough with a usable top. Was trying to figure a way that may be deemed legal to have a bar that was sleeved and pinned in place and quickly removed for those days I want to run the top. I may be sitting on the floor in my aluminum buckets seats if I can't overcome the issue

Cheers

Bill Chasser Jr
TD4834
W. A. Chasser Jr

Hello again Geoff
I really like the design; but you've spent all this time on building a very good roll bar based on the limitations of the application. Then you've gone and used hardware store bolts- of unknown origin and questionable shear strength. Please, go with grade 8 or AN from a known source. Anything else for this critical application is a false economy in MHO.
Regards
Hiram
Hiram Kelley

Really nifty. Reminds me of the substructure I built into ours, but I've held off fabricating our rollbar until the convertible top goes on. Have you checked the elevation with respect to the rag top? I have a hunch it is too high; hope I'm wrong.
Since we usually run a hardtop, the convertible top frame will be modified to be removable utilizing four of the chrome wingnuts, rather than permanently attached with wood screw. If your bar interferes with raising & lowering of the top, you might want to consider a detachable top, too.
JRN JIM

Jim; Yes, I installed the rag top and raised and lowered it with the rollbar in place. I might want to install some kind of cloth cover on the hoops so the metal doesn't mark up the canvas, however, as the cloth slides over the hoops.
Hiram, thanks for the suggestion; I'll source some grade 8s from Mcmasters. Good point!
Geoffrey M Baker

Here's the rollbar primer coated and sitting on the plywood, which has been cut out for all screws and the rollbar mount (which was a real pain, getting under the car and marking everything in place!)

Geoffrey M Baker

I left out an important picture: here is the front bar mounted in the brackets with the plates in position so you can see how it mounts under the plywood floor.

Geoffrey M Baker

Nice work! Well thought out and fine craftsmanship. I prey you will never need to test it. I have a TC and a TD that have been rolled. Each incident cost a man his life.
Now you have a reasonable anchor point to install real three point seat belts.
Nobody wants to talk about it (understandably) but these little cars can and do roll over.
David.
D. Sander

Nice work Geoffery! That is the best anchor system I've seen. A roll bar is only as good as it's mounting surface. Nice job! PJ
Paul S Jennings

OK, it's installed and here are some pix:

Geoffrey M Baker

another

Geoffrey M Baker

and here's a video of opening the top the rollbar!

https://onedrive.live.com/redir?resid=BC0BE72B68A44457%2128447
Geoffrey M Baker

Here is a picture of the mounts all ready for final assembly.

Geoffrey M Baker

Here is the draft excluder. Because I was cutting six large holes in the rear floor, it would be impossible to do a good job of sealing each hole; so instead, I just installed a thin sheet of aluminum under the plywood floor and between the mounts and the rollbar. Once everything is bolted in, it will provide an airtight and weathertight barrier.

Geoffrey M Baker

And here is plywood floor and the rollbar in place waiting for final assembly.

Geoffrey M Baker

That's about all, folks, I hope this helps anyone else planning - or thinking - about installing a rollbar. It can be done. What's more, if you look at the video in the link I posted, you may notice that there is PLENTY of room ... you could probably make the rollbar a good two inches taller than mine and still be able to raise and lower the top (at least, on a two bow top... can't say how it would work on a three bow top.)
Good luck!
Geoffrey M Baker

Note for Hiram: based on your recommendation, I substituted class 8 bolts throughout. I guess I don't know much about this kind of thing, I always thought a bolt was a bolt! But for an additional $9, I now have even more peace of mind! And I have to say, having a rollbar makes me feel so very much more relaxed when driving this old beauty :)
Geoffrey M Baker

Goeff,
I can't seem to get the link to work.

Steve
Steve Wincze

Steve, it works for me, here it is again:

https://onedrive.live.com/redir?resid=BC0BE72B68A44457%2128447

If you really want to see it but cannot access it, send me your email address and I will email you the file - it's almost 2mb in size.
Geoffrey M Baker

This thread was discussed between 20/11/2014 and 24/11/2014

MG TD TF 1500 index

This thread is from the archives. Join the live MG TD TF 1500 BBS now